In an electrostatographic reproducing apparatus commonly used today, a photoconductive insulating member may be charged to a negative potential, thereafter exposed to a light image of an original document to be reproduced. The exposure discharges the photoconductive insulating surface in exposed or background areas and creates an electrostatic latent image on the member which corresponds to the image areas contained within the original document. Subsequently, the electrostatic latent image on the photoconductive insulating surface is made visible by developing the image with a developing powder referred to in the art as toner. During development, the toner particles are attracted from the carrier particles by the charge pattern of the image areas on the photoconductive insulating area to form a powder image on the photoconductive insulating area. This image may be subsequently transferred or marked onto a support surface such as copy paper to which it may be permanently affixed by heating or by the application of pressure. In some of these electrostatic marking systems, a photoreceptor belt or drum or an Intermediate Transfer Belt (ITB) is generally arranged to move in an endless path through the various processing stations of the xerographic marking process. The present invention will be described in a system where the developed image is transferred from an ITB to a substrate as selected by the user. However, a system where the transfer is from a photoconductor is also included. Substrate refers to the print medium selected by the user.
Following transfer of the toner image or marking, the substrate may be removed from the system by a user or may be automatically forwarded to a finishing station where the copies may be collected, compiled and stapled and formed into books, pamphlets or other sets. A critical portion in this xerographic process is the toner transfer step prior to fusing of the toner to the receptor or paper. This step is referred to as final transfer.
Xerographic toner transfer relies on designing control parameters that are robust to many noises. While transfer robustness can be optimized, it can never be optimized for all substrates, toners and environments. In all xerographic processes, the substrate (including paper) and the toner used are key and critical to ideal final images. Substrate characteristics that play an important part in this process are type of substrate, i.e. recycled paper, transparency, coated or non-coated, substrate water content, dielectric properties, temperature, weight in grams per square meter (GSM), etc. Each machine has built-in software or algorithms that control transfer system set points. The present invention provides a method or system to enhance these algorithm parameters to optimize image quality. In addition to differences in substrate conditions that need to be considered when providing new algorithms are toner performance and age of the machine and machine components. Machine and component age affect transfer system electrical characteristics especially for a machine using an ITB and pressure transfer system.